Steven Bradley Mell, 52, of Far Hills, the president and CEO if W.H. Mell Associates in Summit, engaged in sexual activity with the girl on his plane and in Readington and Bedminster between July and December of 2017, according to authorities. The girl was younger than 16, according to court records.

Mell, who goes by his middle name, pleaded guilty in federal court to one count of interstate travel to engage in illicit sexual conduct and one count of receipt of child pornography and was sentenced to seven years in prison in June as part of a plea deal.

He also admitted to a single charge of child endangerment in Superior Court in Hunterdon County and was sentenced June 28 to a three-year concurrent prison term, according to the prosecutor’s office.

Mell was scheduled to be sentenced Friday, but the hearing was moved up to June 28 because he had to report to federal prison by Tuesday, a court employee said. Bureau of Prisons records indicate he is serving his term at Federal Correctional Institute Allenwood Low in Pennsylvania, a low-security facility.

Acting Hunterdon County Prosecutor Michael J. Williams said Wednesday that Mell’s arrest was the result of an investigation by his office’s special victims unit. Mell communicated with the 15-year-old girl via text messages and Snapchat starting in May of 2017, according to the federal complaint. He asked her if she knew how to perform a sex act, according to the complaint, and then invited her to his Far Hills home.

They had sexual contact June 20 and July 5, and then on his plane July 20 while he was flying her between Somerset Airport and Cape Cod, the complaint said. On the flight back, he put the plane in autopilot during one sexual act, the complaint said.

He also received sexually explicit photos of the girl, authorities said.